Background: Deep vein thrombosis (DVT) or venous thromboembolism is a fatal complication of patients undergoing elective hip surgeries. Not much evidence is provided in the Indian literature regarding the incidence of DVT in the Indian population and ideal prophylaxis for the same. This issue has gained much importance in recent history due to the increase in a number of elective hip surgeries. Low-molecular-weight (LMW) heparin is commonly used for chemoprophylaxis against DVT. Our study is to identify the role of LMW heparin (enoxaparin) for prophylaxis against DVT. Materials and Methods: The present study is a prospective study for the role of enoxaparin in prophylaxis against DVT in patients of elective hip surgeries carried out over a period of 2 years. A total of 110 patients were selected based on the stringent inclusion and exclusion criteria. Randomization was done and patients were divided into two groups of 55 patients each. Group 1 (case) received postoperative enoxaparin at a dose of 40 mg subcutaneous daily for 7 days whereas Group 2 (control) did not receive any prophylaxis, following which color Doppler was performed on all patients. Results: The overall incidence of DVT in our study group was found to be 23.6%, of which 61.5% had distal thrombus and 28.5% had thrombus in the proximal vein. The incidence of DVT in case group was 12.5% compared to control group, in which the incidence of DVT was found to be 34.5%; hence, statistically significant difference (P = 0.0071) in the incidence of DVT was found in both groups. Duration of surgery and patient's age were two most significant risk factors associated with the occurrence of DVT. No statistically significant difference was noted regarding postoperative bleeding complications between two groups (P > 0.05). Conclusion: DVT/venous thromboembolism is relatively less common in Indian patients following elective hip surgeries as compared to the Western population, and LMW heparin is a safe and effective method of prophylaxis against DVT.

DVT is a major and a common preventable cause of death worldwide.[1] It affects approximately 0.1% of person per year. The incidence of postoperative deep vein thrombosis (DVT) within the western unprotected patient population ranges between 45% and 80% and about 1.2% of these develop fatal pulmonary thromboembolism with a mortality rate of 0.5%–2%.[2] However, postoperative DVT is regarded as uncommon in the Indian population, but there is not much evidence in the literature to support it. An accurate diagnosis of DVT is critical to prevent the potentially fatal acute complication of pulmonary embolism and long-term complications of thrombophlebitis and pulmonary hypertension.

To appropriately target prophylaxis, patients at risk for the development of DVT must be identified. Several patient characteristics have been identified as independent risk factors such as age, gender, duration of surgery, a length of hospital stay, and obesity, of this duration of surgery conveys the greatest risk.[3],[4],[5]

Screening for DVT can be done invasive as well as by noninvasive methods such as contrast venography (CV), labeled fibrinogen,[6] and color Doppler sonography.[7] CV is considered the gold standard for screening as well as diagnosis of DVT. However, color Doppler duplex sonography (CCDS) is now the most commonly used modality for the screening of patients with DVT as it is noninvasive and easy to perform.

Thromboprophylaxis for DVT can be achieved by pharmacological as well as mechanical means. Low-molecular-weight (LMW) heparin is now considered the gold standard for prophylaxis against DVT due to its longer half-life and higher bioavailability compared to unfractionated heparin.[8] Bleeding is the most common complication of using LMW heparin. This study is conducted to examine the safety and effectiveness of LMW heparin (enoxaparin) in prophylaxis against DVT in patients undergoing elective hip surgeries.

Materials and Methods

This prospective study was conducted at the Department of Orthopaedics, S. N. Medical College, Agra, from January 2013 to October 2014 based on the strict inclusion and exclusion criteria [Table 1]. All good clinical practice guidelines were followed and the Hospital Medical Research Committee approved the study. The cases were randomized into two groups of 55 patients each: Group 1 LMW heparin group/case group and Group 2 control group. Enrolled patients in Group 1 received 40 mg of enoxaparin subcutaneous once daily beginning 12 h after surgery, whereas enrolled patients in Group 2 did not receive any pharmacological thromboprophylaxis. A conventional protocol followed regarding mobilization of the patient, and no patient immobilized beyond 72 h of surgery. All patients were subjected to CCDS on the 7th postoperative by an experienced radiologist using a 5–12 MHz linear transducer and a 3–5 MHz convex probe using in obese patients.

Assessment of the safety of enoxaparin was done based on the suction drain volume and fall in postoperative hemoglobin and platelet count.

Statistical analysis

The mean and standard deviation of each group was calculated, and a two-tailed t-test was used to compare two means, and the Chi-square test was used for categorical data and to calculate the P value. The significance level was set at 0.05.

Results

The mean age of enrolled patients in our study is 62.4 + 9.55 years. There were 50 males and 60 females in our study group. Regarding the type of surgery performed, fixation of proximal hip fractures was the most common operation carried out in both groups accounting for 50.9% and 45.4% in Group 1 and Group 2, respectively, followed by bipolar hemiarthroplasty which accounts for 27.3% and 29% in Group 1 and Group 2, respectively. Total hip arthroplasty accounted for 21.8% and 25.4% of cases in Group 1 and Group 2, respectively [Table 2].

Age >40 years was the most common risk factor in both groups associated with 70.1% of patients in Group 1 and 80% of patients in Group 2. Duration of surgery >1 h was associated with 56.4% and 63.6% in Group 1 and Group 2, respectively [Table 3].

Of the 110 patients enrolled in our study, 26 patients had signs of postoperative DVT, i.e., 23.6% of all cases, whereas 84 patients had no evidence of DVT [Table 4]. There were 10 proximal and 16 distally located thrombi. The incidence of DVT in total hip arthroplasty patients was 8.4% and 45.4% in Group 1 and Group 2, respectively, whereas the incidence of DVT in bipolar hemiarthroplasty and proximal hip fracture fixation was 13.3%/37.5% and 14.2%/32% in Group 1 and Group 2, respectively. Thus, the incidence of DVT in patients who received LMW heparin for prophylaxis was statistically significantly low when compared to patients who did not receive any prophylaxis (P = 0.0071, Chi-square test).

Regarding the safety of LMW heparin, we found no statistically significant difference in clinical parameters such as preoperative and postoperative hemoglobin, prothrombin time, platelet count, and suction drain volume between both groups [Table 5].

Venous thromboembolism remains a significant complication of major orthopedic surgery, despite the use of the preventive measure. Few studies using different modalities of diagnosis of DVT have been reported from Asia. These studies have reported widely varying incidence rates ranging from 2.6% to 53.3%. In our study, the incidence of DVT among all patients under the study was found to be 26.4% on color Doppler ultrasonography examination, of which 73% was considered to be proximal DVT and 27% had evidence of distal DVT. There was not a single case of pulmonary embolism. These results are comparable to those results published by Bhan et al.,[9] who reported 23.3% of the incidence of DVT. The incidence of DVT in patients who received thromboprophylaxis was 12.7% compared to the patients who did not receive thromboprophylaxis (34.5%). Thus, the impact of DVT in patients who received LMW heparin was statistically significantly lower (P = 0.0071, Chi-square test) compared to patients who did not receive any LMW heparin. These findings were comparable to the results of Turpie et al.,[10] who reported that enoxaparin reduced the incidence of DVT after elective surgeries from 51% to 11%. However, Agarwala et al.[11] reported the incidence of DVT after thromboprophylaxis with LMW heparin to be 34.4%. These findings were significantly higher than findings in our study.

The mean baseline hemoglobin of the patients was 11.85 g/dL and the mean hemoglobin on the 2nd postoperative day was 10.21 + 1.26 in patients who received prophylaxis compared to patients who did not receive any prophylaxis and had a mean hemoglobin level of 10.65 + 1.11 g/dL. The fall in hemoglobin was not found to be statistically significant in both groups (P > 0.05, Student's t-test).

The mean postoperative blood loss in Total hip replacement (THR), bipolar hemiarthroplasty, and fixation of proximal hip fractures were 289.7 mL, 234.8 mL, and 140.7 mL, respectively, in patients who received enoxaparin compared to patients of the control group in which the mean postoperative blood loss was 242.5 mL, 180.2 mL, and 130.6 mL, respectively. These values were also statistically not significant between two groups (P > 0.05). Thus, bleeding complications were not found to be significant in thromboprophylaxis with LMW heparin (enoxaparin). These findings were comparable to the results of Turpie et al.,[10] who did not find any statistical significance in the mean hemoglobin level and the mean postoperative blood loss between patients who received enoxaparin prophylaxis and patients who did not receive any prophylaxis.

From our study, we concluded that the incidence of DVT in postoperative orthopedic patient undergone elective hip surgeries is lower in the Indian population than Western society and thrombus in deep veins is more common than proximal veins. The primary reason for this difference in incidence is still not known. However, several factors such as genetic variations, environmental factors, differences in socioeconomic status, and dietary habits of people may differ because of the low incidence of DVT in the Indian population. Another important factor may be the lack of awareness of patients and differences in diagnostic modalities as compared to the west.

Age of the patients and duration of surgery are the primary risk factors associated with the development of DVT, irrespective of the sex of the patients.

From our study, we also concluded that short-term prophylaxis with LMW heparin (enoxaparin 40 mg subcutaneous) started in 12 h postoperatively leads to a significant reduction in the incidence of DVT. Moreover, since no major bleeding episodes or fall in hematocrit was seen in our study group in immediate and early postoperative period, we concluded that short-term prophylaxis with LMW heparin is a safe and effective method in patients undergoing elective hip surgeries.

Since DVT is a potentially life-threatening complication following elective hip surgeries, we recommend that short-term prophylaxis with LMW should start in the immediate postoperative period.

Conclusion

From our study, we concluded that short-term prophylaxis with LMW heparin (enoxaparin 40 mg subcutaneous) started in 12 h postoperatively leads to a significant reduction in the incidence of DVT. Moreover, since no major bleeding episodes or fall in hematocrit was seen in our study group in immediate and early postoperative period, we concluded that short-term prophylaxis with LMW heparin is a safe and effective method in patients undergoing elective hip surgeries.

Since DVT is a potentially life-threatening complication following elective hip surgeries, we recommend that short-term prophylaxis with LMW should start in the immediate postoperative period.